But the business in the generation of an egg is very different from this; for neither does the semen, or rather the ‘geniture,’ proceeding from the male in the act of intercourse, enter the uterus in any way, nor has the hen, after she conceives, any particle of excrementitious matter, even of the purest kind, or any blood in her uterus which might be fashioned or perfected by the discharge of the male. Neither are the parts of the egg, the membranes, to wit, and the fluids, produced by any kind of coagulation; neither is there any thing like curdled milk to be discovered in the uterus, as must be obvious from the foregoing exercises. It follows, therefore, and from thence, that neither does the conception, whence the animal springs, as the herb arises from a fruitful seed, comport itself in the manner Aristotle imagined, since this takes place in viviparous animals in the same way as the egg is formed in oviparous animals, as he himself avows, and as shall be demonstrated by and by in our observations. Because it is certain that eggs of every description—prolific and barren—are engendered and formed by the hen singly, but that fecundity accrues from the male alone;—the cock, I say, contributes neither form nor matter to the egg, but that only by which it becomes fertile and fit to engender a chick. And this faculty the cock confers by his semen (genitura), emitted in the act of intercourse, not only on the egg that is already begun, or is already formed, but on the uterus and ovary, and even on the body of the fowl herself, in such wise that eggs which have yet to be produced, eggs, none of the matter of which yet exists either in the ovary or in any other part of the body, are thence produced possessed of fecundity.
EXERCISE THE THIRTY-SECOND.
Nor in the manner imagined by physicians.
Conception, according to the opinion of medical men, takes place in the following way: during intercourse the male and female dissolve in one voluptuous sensation, and eject their seminal fluids (genituræ) into the cavity of the uterus, where that which each contributes is mingled with that which the other supplies, the mixture having from both equally the faculty of action and the force of matter; and according to the predominance of this or of that geniture does the progeny turn out male or female. It is farther imagined that immediately after the intercourse, the active and passive principles cooperating, something of the conception is formed in the uterus. For contrary to the Aristotelians, they maintain that the male is no more the efficient cause of generation than the female, but some mixture of the two; and that neither the menstrual blood nor its purest part is the prime matter of the conception, but the spermatic fluid; whence the first particles or their rudiments are spoken of as spermatic, these at an after period being nourished and made to increase through the blood.
But it is obvious that neither is the egg engendered by the cock and hen in this way; for the hen in the act of intercourse emits no semen from which an egg might be formed; nor can aught like a seminal fluid of the hen be demonstrated at any time; and indeed the animal is destitute of the organs essential to its preparation, the testes and vasa spermatica. And though the hen have an effective force in common with the cock (as must be manifest from what precedes), and it is a mixture of some sort that renders an egg fruitful, still this does not happen according to the predominance of the genitures, or the manner of their mixture, for it is certain, and Fabricius admits it, that the semen of the cock does not reach the cavity of the uterus; neither is there any trace of the egg to be discovered in the uterus immediately after intercourse, and as its consequence, although Aristotle himself repeatedly avers that there is, asserting that “something of the conception forthwith ensues.” But I shall by and by demonstrate that neither does any such imaginary mixture of seminal fluids take place in any animal, nor that immediately upon intercourse, even of a fruitful kind, is there anything in the shape of semen or blood, or of the rudiments of an embryo present or demonstrable in the cavity of the uterus. Nothing is found in the egg or embryo which leads us to suppose that the semen masculinum is either there contained or mingled. The vulgar notion of the chalazæ being the tread of the cock is a sheer mistake; and I am surprised, since there are two of them, one in either end of the egg, that no one has yet been found to maintain that this was the cock’s seed, that the hen’s. But this popular error is at once answered by the fact that the chalazæ are present with the same characters in every egg, whether it be fertile or barren.
EXERCISE THE THIRTY-THIRD.
The male and the female are alike efficient in the business of generation.
The medical writers with propriety maintain, in opposition to the Aristotelians, that both sexes have the power of acting as efficient causes in the business of generation; inasmuch as the being engendered is a mixture of the two which engender: both form and likeness of body, and species are mixed, as we see in the hybrid between the partridge and common fowl. And it does indeed seem consonant with reason to hold that they are the efficient causes of conception whose mixture appears in the thing produced.
Aristotle entertaining this opinion says:[225] “In some animals it is manifest that such as the generator is, such is the engendered; not, however, the same and identical, not one numerically, but one specifically, as in natural things. A man engenders a man, if there be nothing preternatural in the way, as a horse [upon an ass] engenders a mule, and other similar instances. For the mule is common to the horse and the ass; it is not spoken of as an allied kind; yet may horse and ass both be there conjoined in a hybrid state.” He says farther in the same place: “It is enough that the generator generate, and prove the cause that the species be found in the matter: for such and such an entire species is still found associated with such and such flesh and bones—here it is Gallias, there it is Socrates.”
Wherefore if such an entire form, as a mule, be a mixture of two, viz.: a horse and an ass, the horse does not suffice to produce this form of a mule in the ‘matter;’ but, as the entire form is mixed, so another efficient cause is contributed by the ass and added to that supplied by the horse. That, therefore, which produces a mule compounded of two, must itself be an ‘adequate efficient,’ and mixed, if only ‘univocal.’ For example, this woman and that man engender this Socrates; not in so far as they are both human beings, and of one and the same species, but in so far as this man and that woman in these bones and muscles constitute human forms, of both of which, if Socrates be a certain mixture, a compound of both, that by which he is made must needs be a mixed univocal compound of the two; i. e. a mixed efficient of a mixed effect. And therefore it is that the male and female by themselves, and separately, are not genetic, but become so united in coitu, and made one animal as it were; whence, from the two as one, is produced and educed that which is the true efficient proximate cause of conception.